qobject: Replace qobject_from_jsonf() by qobject_from_jsonf_nofail()

Commit ab45015a "qobject: Let qobject_from_jsonf() fail instead of
abort" fails to accomplish its stated aim: the function can still
abort due to its use of &error_abort.

Its rationale for letting it fail is that all remaining users cope
fine with failure.  Well, they're just fine with aborting, too; it's
what they do on failure.

Simply reverting the broken commit would bring back the unfortunate
asymmetry between qobject_from_jsonf() and qobject_from_jsonv(): one
aborts, the other returns null.  So also rename it to
qobject_from_jsonf_nofail().
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NThomas Huth <thuth@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Message-Id: <20180806065344.7103-7-armbru@redhat.com>

include/qapi/qmp/qjson.h

@@ -15,11 +15,13 @@
 #define QJSON_H
 
 QObject *qobject_from_json(const char *string, Error **errp);
-QObject *qobject_from_jsonf(const char *string, ...) GCC_FMT_ATTR(1, 2);
 QObject *qobject_from_jsonv(const char *string, va_list *ap, Error **errp)
     GCC_FMT_ATTR(1, 0);
 
-QDict *qdict_from_jsonf_nofail(const char *string, ...) GCC_FMT_ATTR(1, 2);
+QObject *qobject_from_jsonf_nofail(const char *string, ...)
+    GCC_FMT_ATTR(1, 2);
+QDict *qdict_from_jsonf_nofail(const char *string, ...)
+    GCC_FMT_ATTR(1, 2);
 
 QString *qobject_to_json(const QObject *obj);
 QString *qobject_to_json_pretty(const QObject *obj);

qobject/qjson.c

@@ -59,7 +59,12 @@ QObject *qobject_from_json(const char *string, Error **errp)
     return qobject_from_jsonv(string, NULL, errp);
 }
 
-QObject *qobject_from_jsonf(const char *string, ...)
+/*
+ * Parse @string as JSON value with %-escapes interpolated.
+ * Abort on error.  Do not use with untrusted @string.
+ * Return the resulting QObject.  It is never null.
+ */
+QObject *qobject_from_jsonf_nofail(const char *string, ...)
 {
     QObject *obj;
     va_list ap;
@@ -68,6 +73,7 @@ QObject *qobject_from_jsonf(const char *string, ...)
     obj = qobject_from_jsonv(string, &ap, &error_abort);
     va_end(ap);
 
+    assert(obj);
     return obj;
 }
 

tests/check-qjson.c

@@ -865,7 +865,8 @@ static void vararg_string(void)
         QString *str;
 
         str = qobject_to(QString,
-                         qobject_from_jsonf("%s", test_cases[i].decoded));
+                         qobject_from_jsonf_nofail("%s",
+                                                   test_cases[i].decoded));
         g_assert(str);
         g_assert(strcmp(qstring_get_str(str), test_cases[i].decoded) == 0);
 
@@ -998,17 +999,17 @@ static void vararg_number(void)
     double valuef = 2.323423423;
     int64_t val;
 
-    qnum = qobject_to(QNum, qobject_from_jsonf("%d", value));
+    qnum = qobject_to(QNum, qobject_from_jsonf_nofail("%d", value));
     g_assert(qnum_get_try_int(qnum, &val));
     g_assert_cmpint(val, ==, value);
     qobject_unref(qnum);
 
-    qnum = qobject_to(QNum, qobject_from_jsonf("%lld", value_ll));
+    qnum = qobject_to(QNum, qobject_from_jsonf_nofail("%lld", value_ll));
     g_assert(qnum_get_try_int(qnum, &val));
     g_assert_cmpint(val, ==, value_ll);
     qobject_unref(qnum);
 
-    qnum = qobject_to(QNum, qobject_from_jsonf("%f", valuef));
+    qnum = qobject_to(QNum, qobject_from_jsonf_nofail("%f", valuef));
     g_assert(qnum_get_double(qnum) == valuef);
     qobject_unref(qnum);
 }
@@ -1042,13 +1043,13 @@ static void keyword_literal(void)
 
     qobject_unref(qbool);
 
-    qbool = qobject_to(QBool, qobject_from_jsonf("%i", false));
+    qbool = qobject_to(QBool, qobject_from_jsonf_nofail("%i", false));
     g_assert(qbool);
     g_assert(qbool_get_bool(qbool) == false);
     qobject_unref(qbool);
 
     /* Test that non-zero values other than 1 get collapsed to true */
-    qbool = qobject_to(QBool, qobject_from_jsonf("%i", 2));
+    qbool = qobject_to(QBool, qobject_from_jsonf_nofail("%i", 2));
     g_assert(qbool);
     g_assert(qbool_get_bool(qbool) == true);
     qobject_unref(qbool);
@@ -1298,7 +1299,7 @@ static void simple_varargs(void)
     embedded_obj = qobject_from_json("[32, 42]", &error_abort);
     g_assert(embedded_obj != NULL);
 
-    obj = qobject_from_jsonf("[%d, 2, %p]", 1, embedded_obj);
+    obj = qobject_from_jsonf_nofail("[%d, 2, %p]", 1, embedded_obj);
     g_assert(qlit_equal_qobject(&decoded, obj));
 
     qobject_unref(obj);

tests/libqtest.h

@@ -77,8 +77,8 @@ void qtest_quit(QTestState *s);
  * qtest_qmp:
  * @s: #QTestState instance to operate on.
  * @fmt...: QMP message to send to qemu, formatted like
- * qobject_from_jsonf().  See parse_escape() for what's supported
- * after '%'.
+ * qobject_from_jsonf_nofail().  See parse_escape() for what's
+ * supported after '%'.
  *
  * Sends a QMP message to QEMU and returns the response.
  */
@@ -88,8 +88,8 @@ QDict *qtest_qmp(QTestState *s, const char *fmt, ...);
  * qtest_qmp_send:
  * @s: #QTestState instance to operate on.
  * @fmt...: QMP message to send to qemu, formatted like
- * qobject_from_jsonf().  See parse_escape() for what's supported
- * after '%'.
+ * qobject_from_jsonf_nofail().  See parse_escape() for what's
+ * supported after '%'.
  *
  * Sends a QMP message to QEMU and leaves the response in the stream.
  */
@@ -99,8 +99,8 @@ void qtest_qmp_send(QTestState *s, const char *fmt, ...);
  * qtest_qmpv:
  * @s: #QTestState instance to operate on.
  * @fmt: QMP message to send to QEMU, formatted like
- * qobject_from_jsonf().  See parse_escape() for what's supported
- * after '%'.
+ * qobject_from_jsonf_nofail().  See parse_escape() for what's
+ * supported after '%'.
  * @ap: QMP message arguments
  *
  * Sends a QMP message to QEMU and returns the response.
@@ -111,8 +111,8 @@ QDict *qtest_qmpv(QTestState *s, const char *fmt, va_list ap);
  * qtest_qmp_vsend:
  * @s: #QTestState instance to operate on.
  * @fmt: QMP message to send to QEMU, formatted like
- * qobject_from_jsonf().  See parse_escape() for what's supported
- * after '%'.
+ * qobject_from_jsonf_nofail().  See parse_escape() for what's
+ * supported after '%'.
  * @ap: QMP message arguments
  *
  * Sends a QMP message to QEMU and leaves the response in the stream.
@@ -552,8 +552,8 @@ static inline void qtest_end(void)
 /**
  * qmp:
  * @fmt...: QMP message to send to qemu, formatted like
- * qobject_from_jsonf().  See parse_escape() for what's supported
- * after '%'.
+ * qobject_from_jsonf_nofail().  See parse_escape() for what's
+ * supported after '%'.
  *
  * Sends a QMP message to QEMU and returns the response.
  */
@@ -562,8 +562,8 @@ QDict *qmp(const char *fmt, ...);
 /**
  * qmp_send:
  * @fmt...: QMP message to send to qemu, formatted like
- * qobject_from_jsonf().  See parse_escape() for what's supported
- * after '%'.
+ * qobject_from_jsonf_nofail().  See parse_escape() for what's
+ * supported after '%'.
  *
  * Sends a QMP message to QEMU and leaves the response in the stream.
  */